Intra prediction device and method involving matrix-based intra prediction

1. An image decoding method performed by a decoding apparatus, the method comprising:

obtaining image information including residual information and prediction-related information through a bitstream;

deriving transform coefficients based on the residual information;

generating residual samples for a current block based on the transform coefficients;

deriving an intra prediction mode for the current block based on the prediction-related information;

generating prediction samples for the current block based on the intra prediction mode; and

generating reconstructed samples for the current block based on the prediction samples and the residual samples,

wherein the image information includes flag information related to whether an intra prediction mode type for the current block is a matrix-based intra prediction (MIP), wherein for the current block of which size is equal to 64×8, the flag information related to whether the intra prediction mode type for the current block is the MIP is included in the image information,

wherein the intra prediction mode type for the current block is determined as the MIP based on the flag information,

wherein based on the flag information related to that the intra prediction mode type for the current block is the MIP, the image information includes MIP mode information, wherein the MIP mode information is related to an MIP mode applied to the current block and the MIP mode is used to derive an MIP matrix for the current block,

wherein the MIP matrix is derived based on (i) a width and a height of the current block for the MIP and (ii) the MIP mode information,

wherein MIP samples for the current block are generated based on the MIP matrix, and

wherein the prediction samples for the current block are generated based on the MIP samples.

2. The image decoding method of claim 1 , wherein reduced boundary samples are derived by down-sampling reference samples adjacent to the current block, and

wherein the MIP samples are generated based on a product between the reduced boundary samples and the MIP matrix.

3. The image decoding method of claim 1 , wherein the height of the current block is four times larger than the width of the current block.

4. The image decoding method of claim 1 , wherein the width of the current block is four times larger than the height of the current block.

5. The image decoding method of claim 1 , wherein the MIP matrix is derived based on three matrix sets classified in accordance with a size of the current block, and

wherein each of the three matrix sets comprises a plurality of matrixes.

6. The image decoding method of claim 1 , wherein the prediction samples are generated by up-sampling the MIP samples.

7. An image encoding method performed by an encoding apparatus, the method comprising:

determining whether a matrix-based intra prediction (MIP) is applied to a current block;

generating prediction samples for the current block based on the determination that the MIP is applied to the current block;

generating prediction-related information based on the determination that the MIP is applied to the current block;

generating residual samples for the current block based on the prediction samples;

deriving transform coefficients based on a transform process for the residual samples;

generating residual information based on the transform coefficients; and

encoding image information including the prediction-related information and the residual information,

wherein the prediction-related information includes flag information, wherein the flag information is related to whether an intra prediction mode type for the current block is the MIP, wherein for the current block of which size is equal to 64×8, the flag information related to whether the intra prediction mode type for the current block is the MIP is included in the image information,

wherein the image information includes MIP mode information based on the flag information related to that the intra prediction mode type for the current block is the MIP, wherein the MIP mode information is related to an MIP mode applied to the current block and the MIP mode is used to derive an MIP matrix for the current block,

wherein the MIP matrix is derived for the MIP based on (i) a width and a height of the current block and (ii) the MIP mode information,

wherein MIP samples for the current block are generated based on the MIP matrix, and

wherein the prediction samples for the current block are generated based on the MIP samples.

8. The image encoding method of claim 7 , wherein reduced boundary samples are derived by down-sampling reference samples adjacent to the current block, and

wherein the MIP samples are generated based on a product between the reduced boundary samples and the MIP matrix.

9. The image encoding method of claim 7 , wherein the height of the current block is four times larger than the width of the current block.

10. The image encoding method of claim 7 , wherein the width of the current block is four times larger than the height of the current block.

11. The image encoding method of claim 7 , wherein the MIP matrix is derived based on three matrix sets classified in accordance with a size of the current block, and

wherein each of the three matrix sets comprises a plurality of matrixes.

12. The image encoding method of claim 7 , wherein the prediction samples are generated by up-sampling the MIP samples.

13. A non-transitory computer-readable digital storage medium for storing encoded image information generated by a method, the method comprising:

determining whether a matrix-based intra prediction (MIP) is applied to a current block;

generating prediction samples for the current block based on the determination that the MIP is applied to the current block;

generating prediction-related information based on the determination that the MIP is applied to the current block;

generating residual samples for the current block based on the prediction samples;

deriving transform coefficients based on a transform process for the residual samples;

generating residual information based on the transform coefficients; and

encoding image information including the prediction-related information and the residual information,

wherein the prediction-related information includes flag information, wherein the flag information is related to whether an intra prediction mode type for the current block is the MIP, wherein for the current block of which size is equal to 64×8, the flag information related to whether the intra prediction mode type for the current block is the MIP is included in the image information,

wherein the image information includes MIP mode information based on the flag information related to that the intra prediction mode type for the current block is the MIP, wherein the MIP mode information is related to an MIP mode applied to the current block and the MIP mode is used to derive an MIP matrix for the current block,

wherein the MIP matrix is derived based on (i) a width and a height of the current block for the MIP and (ii) the MIP mode information,

wherein MIP samples for the current block are generated based on the MIP matrix, and

wherein the prediction samples for the current block are generated based on the MIP samples.